Not Applicable
Not Applicable
The present invention relates to techniques for casting plumbing fixtures. It is especially well suited for casting toilet bowls having substantially closed rims.
Toilets have often been cast from ceramic slurries. Typically, the slurry was placed in a porous mold which caused the ceramic material to deposit along the mold walls due to capillary attraction through mold pores. As a hollow remained inside of the material that had been deposited on the mold walls, excess slurry could be drained from the mold interior to clear trapways and other water pathways.
The newly-formed fixture was referred to as xe2x80x9cgreenwarexe2x80x9d. xe2x80x9cGreenwarexe2x80x9d more generally refers to an unfired ceramic, usually one with substantial moisture content, regardless of the color of the item. The greenware toilets were then typically allowed to air dry and then fired in a kiln.
Various types of automated equipment for casting ceramic plumbing fixtures are known (e.g. U.S. Pat. No. 4,948,087xe2x80x94lavatories; U.S. Pat. No. 5,299,624xe2x80x94toilets). Such equipment can close, pressurize, drain, and open multiple molds to form multiple plumbing fixtures or fixture parts at the same time. With respect to toilets, such equipment works best for toilets that are designed with open rim bottoms. When the toilet rim is designed with a closed bottom, this type of molding requires the rim and bowl to be molded separately (and then joined together, preferably while the two pieces of greenware are still soft). See generally U.S. Pat. No. 2,565,356. Unfortunately, the weight of rims is sometimes so great that this process can cause bowl walls to deform during the process unless extreme care is used (thereby slowing the process considerably).
To date the prior art had not provided an optimal solution for this problem. The art has been accepting a certain amount of waste, deformity, and/or slower production rates. Thus, it can be seen that a need exists to develop improved techniques for casting such items.
In one aspect the invention provides a method for casting a plumbing fixture having a bowl and a rim. One casts a bowl portion of a plumbing fixture, and a rim portion of the plumbing fixture separately from the bowl portion. One then places the rim portion in contact with the bowl portion when both are upside down and both are greenware. Thereafter, one allows the bowl portion and rim portion to bond together and dry.
In preferred methods the casting of the bowl portion involves the use of multiple mold parts to form the bowl portion, followed by removal of a bottom one of the mold parts while the bowl portion is in an upside down position. The plumbing fixture can be a toilet having a rim with an at least partially closed bottom.
In other preferred aspects, the bowl portion is cast in a four part mold supported by a press unit. The components of the press unit control the position of two side mold parts in a manner such that they can continue to support the cast bowl portion upside down when the top of the bowl portion is exposed.
In another form the invention provides a molding apparatus for casting a plumbing fixture having a bowl and rim. There is a frame member, a top mold part, two side mold parts and a bottom mold part. The mold parts are capable of forming an upside down portion of a plumbing fixture when the mold parts are in a molding position.
There are also mold reciprocating members connected to the mold parts and to the frame member to move the mold parts between the molding position and retracted positions in an automated manner. The mold reciprocating members and the mold parts are constructed and arranged so as to be able to move the bottom mold part down relative to the side mold parts when the side mold parts are still in the molding position.
Preferably the mold reciprocating members include hydraulic rams. The mold reciprocating members and the mold parts can be constructed and arranged to move both the top and bottom mold parts away from the side mold parts while the side mold parts are still in the molding position. When the molding apparatus forms a bowl, the molding apparatus can be used with a rim support member capable of moving a rim into contact with the bowl after the bottom mold part is moved away from the side mold parts and while the bowl is still at least partially between the side mold parts. The apparatus can also include a conveyor extending below a bottom of the molding apparatus.
In still another form the invention provides cast plumbing fixtures produced by the above methods.
It will be appreciated that the invention reduces deformities (and associated waste) that are caused by conventional methods of casting and assembling such toilets. Deformities are further reduced when using the present invention because the most fragile portions of the bowl wall remain supported by mold parts when the bowl is first pressed onto the rim. Equipment for facilitating the automation of these methods is also provided.
The invention therefore provides:
a. a method for casting a toilet bowl and rim (and analogous plumbing fixtures such as a lavatories and bath tubs) wherein the incidence of deformation of the bowl during assembly of the toilet parts is substantially reduced;
b. a method for casting such fixtures which lends itself to automation and increased rates of production; and
c. an apparatus which can carry out the method described herein.
These and still other advantages of the present invention will be apparent from the description which follows. In the detailed description below preferred embodiments of the invention are described with reference to the accompanying drawings. These embodiments do not represent the full scope of the invention. Rather the invention may be employed in other embodiments. Reference should therefore be made to the claims herein for interpreting the full breadth of the invention.